I've heard that Mezari were at first just reskined version of Vaulters. But in Endless Space 2 (If we choose Mezari during United Empire's main quest) and in Endless Legend they are clearly different factions. I have never played Dungeon Of Endless, and haven't really paid attention to story of either of these factions in Endless Legend, so sorry for lacks in my knowledge. In EL both of them have the same traits (they can teleport, have the same quest etc, and they have only a few cosmetic differences. So, what is the origin of mezari (who later colonized the raia and formed the united empire), and are they even related to vaulters? 

The Vaulters are basically the descendandts of the Vaulters.

Theres not much known about the Mezari besides, that it seems to be the first human empire.

It Somehow collapsed but some of it's parts still remain.

Notable:

UE > Ex mezari colony

Vaulters > Mezari that crashlanded on AUriga

Horatio > Mezari bilionaire who had enough of them and went on a solo voyage

Pilgrims > Split off the UE

What CountBlue said. Essentially, all humans in the Endless universe are biologically descended from the Mezari empire, which from what we know so far is the original human empire. Yes, Amplitude doesn't like to call them humans, but most likely they are a species evolved from apes from an Earth-like planet around a star similar to our sun. The Mezari were a scientifically-minded people who came from a planet similar to Earth. Eventually they discovered spaceflight and established an empire. For some reason, the empire collapsed and their eventual descendants were stranded on a variety of planets, most notably - Auriga and Raia. Thus, the Imperials, the Vaulters and the Pilgrims are all direct descendants of the Mezari humans, although the Vaulters have kept their signature symbol. A Mezari UE also has the same symbol. Whether the Roving Clans, Ardent Mages and Sisters of Mercy on Auriga are also of Mezari origin or belonging to some other human civilization is of course questionable, but most likely are also humans. Most likely, however, the very origins of the Mezari are the origins of all of humankind in the Endless world.

Horatio is the only individual we know of who has actual direct memories of the Mezari Empire, although it most likely collapsed while he traveled in cryostasis to Horatio Prime. Also his extensive and bizarre genetic modification have definitely made him something else entirely, although he is still of Mezari origins.

dobyk wrote:

Horatio is the only individual we know of who has actual direct memories of the Mezari Empire, although it most likely collapsed while he traveled in cryostasis to Horatio Prime. Also his extensive and bizarre genetic modification have definitely made him something else entirely, although he is still of Mezari origins.

Kinete Muldaur's biography mentions that she was a part of the Mezari military before joining the academy, so there's two.

Think of the Mezari as the precursors to every human civilization in the Endless Galaxy 

[Spoilers for Vaulter Main Quest] 

The Mezari homeworld is called Mezan (though it's now a barren wasteland due to overexploitation). Over time the Mezari launched colonization vessels across the galaxy, settling different worlds and it is implied, that they created a vast empire. 

The Tikanan were the products of one of their colonies and so is the UE. 

Eventually, a Mezari cryo-colonization ship crashlanded on Auriga and the surviving colonists used the ship as a fortress on Auriga, eventually creating vast underground cities.

Several centuries later the former Mezari colonists would become the Vaulters. 

But the two Civilizations differ vastly due to the time separation between them.
Also, there's no confirmed Mezari other than Horatio, Kinete Muldaur and Varb St Zouiena left in the universe except for the UE Quest in which you can turn into the Mezari. 

In Varb's case, he was part of the Zolya clan 

"If pressed to respond, Varb would indicate that his life began as a hydroponic farmer on a space station, a member of the Zolya Clan and a happy husband and father."

The DEV's confirmed that the Zolya clan is a prominent Mezari Clan. 

dobyk wrote:

Most likely, however, the very origins of the Mezari are the origins of all of humankind in the Endless world.

Mezan is the Mezari homeworld (the Vaulters found it) but it's in the same state as Tchinomy, or possibly worse, and sounds like it's well known around the galaxy 

Suis3i wrote:

dobyk wrote:

Most likely, however, the very origins of the Mezari are the origins of all of humankind in the Endless world.

Mezan is the Mezari homeworld (the Vaulters found it) but it's in the same state as Tchinomy, or possibly worse, and sounds like it's well known around the galaxy 

Tchinomy is at least habitable with tier 1 technology. Mezan sounds like it got Craver'd so hard it turned into a barren planet.

As a newcomer to the Endless lore this thread is very enlightening. My first contact was Endless Legend, but I didn't py to much attention to all the backstories involved. Endless Space 2 now has hooked me and it is interesting to discover all the links burried in there. Thanks to all you loremasters.

Thank you for explaining everything to me.

I echo the sentiments--nice work, Endless archaeologists. I really don't have anything to add!

IO start endless legend today with mezari